A thermal sensor is used for measuring temperatures of a coolant fed to an engine of a vehicle. Conventionally, this thermal sensor is attached into a housing bushing that is installed in a coolant pipe. A method for attaching the thermal sensor into the housing bushing is described in Patent Document 1.
Patent Document 1: JP-2001-241584 A
In this attaching method, a thermal sensor 110 is fixed, with a clip 148 (shown in FIG. 7B), into a housing bushing 130 installed in a coolant pipe 50, as shown in FIG. 7A. Further, the housing bushing 130 has a slit 134 that is circumferentially formed. The clip 148 is laterally inserted into the slit 134 just when the thermal sensor 110 is being pushed into the housing bushing 130.
However, this insertion of the clip is not easy work since the insertion is required to be performed just when the thermal sensor 110 is being pressed to a water-leakage preventing O-ring (not shown) within the housing bushing 130. Further, a position of the thermal sensor 110 is not predetermined, so that the thermal sensor 110 is not easily connected with a connector, which prevents the connection procedure from being automated. Furthermore, the thermal sensor 110 is rotatable with respect to an axis of the housing bushing 130. In a condition where a harness (not shown) attached to the thermal sensor 110 is vibrated during vehicle driving, the thermal sensor 110 possibly rotates to thereby damage the O-ring, resulting in leakage of the coolant.